Hoist

ABSTRACT

This hoist includes upper and lower rail-engaging roller assemblies and is suspended from a point offset from the center of gravity so that the upper and lower roller assemblies are urged into contact with the rail bearing surfaces. The lower roller assembly includes a self-aligning mechanism by which the rollers are maintained in engagement with misaligned rail surfaces. The self-aligning mechanism includes a shaft having aligned end portions, which are journaled into the hoist brackets, and oppositely cranked intermediate portions mounting the rollers, the rollers being automatically relocated under pressure from the hoist to compensate for rail misalignment.

United States Patent [191 Thorp, Jr. I

[ June 28, 1974 I HOIST [75] Inventor: James T. Thorp, Jr., Edwardsville,

' Ill.

[73] Assignee: Champion Hoist Company, St.

Louis, Mo.

[22] Filed: Dec. 6, 1971 [21] Appl. No.: 205,038

[52] US. Cl 187/95, 180/1 VS, 295/36 [51] Int. Cl B66b 7/02 [58] Field of Search 308/6; 182/142;

187/10-14, 95; 180/1 VS; 280/6 R, 6.1];

[56] References Cited UNITED STATES PATENTS 2,588,458 3/1952 Allphin 187/10 2 929,420 3/1960 Gresdel 308/6 3 109,506 11/1963 Schroter et al. 280/6 R X 3 365,253 l/l968 Haller 308/6 3 464.520 9/1969 Anderson 182/142 FOREIGN PATENTS OR APPLICATIONS 5/1966 Great Britain 182/142 Primary Examiner-Evon C. Blunk Assistant Examiner-Douglas D. Watts 5 ABSTRACT This hoist includes upper and lower rail-engaging roller assemblies and is suspended from a point offset from the center of gravity so that the upper and lower roller assemblies are urged into contact with the rail bearing surfaces.

The lower roller assembly includes a self-aligning mechanism by which the rollers are maintained in engagement with misaligned rail surfaces. The self-aligning mechanism includes a shaft having aligned end portions, which are journaled into the hoist brackets, and oppositely cranked intermediate portions mounting the rollers, the rollers being automatically relocated under pressure from the hoist to compensate for rail misalignment.

2 Claims, 7 Drawing Figures HOIST This invention relates in general to a rail and hoist assembly and particularly to a hoist assembly which incorporates a self-aligning, rail-riding mechanism.

Hoists are commonly used for industrial purposes, for example on building sites and in factories where it is desirable to have a means of transporting material and equipment from one elevation to another.

Such hoists commonly incorporate a platform or container balanced by means of a counterweight assembly, the hoist and the counterweight riding on a pair of substantially upright rails. One of the problems inherent in this rail arrangement is that the manner of attaching individual rails to a wall or similar support renders it exceedingly difficult to maintain the rail surfaces in alignment. Even when shims are utilized it is difficult to achieve true alignment over the complete length of the rails.

It is highly desirable that vibration or chattering between the hoist rollers and the rails be avoided. Some hoist systems attempt to overcome this problem by suspending the hoisting element eccentrically so that the rollers engage the rails under pressure. Theoretically, given perfect rail alignment this system would work well. However, the inevitable misalignment of rails tends to cause the hoist to rack and bind because of the uneven distribution of pressure on the rails. In addition the uneven distribution of pressure results in wear of the rollers greatly in excess of that which occurs when the pressure is evenly distributed.

SUMMARY OF THE INVENTION This rail and hoist assembly includes a self-aligning mechanism which insures that the hoist rollers bear evenly on the rail riding surfaces even though such rail surfaces are misaligned.

The arrangement by which the self-aligning is accomplished permits the hoist rollers to maintain a pressure engagement with the rails thereby avoiding unnecessary vibration and chatter between the hoist rollers and rails and precluding excessive wear of the rollers.

The hoisting element includes upper and lower bracket means each carrying roller assemblies engaging the rail surfaces and at least one of said roller assemblies provides a self-aligning, rail-riding means. The self-aligning means includes an elongate shaft mounted in journal relation to the bracket means and the shaft includes a first portion offset from the journal axis, and a second portion offset from the journal axis and from the first portion. The rail-riding means includes first and second rail-engaging rollers rotatively mounted to said first and second offset shaft portions.

The suspension point of the hoisting element is disposed inwardly of the center of gravity toward the rails so that the upper roller assembly is-urged into engagement with the rearward railbearing faces and the lower roller assembly is urged into engagement with the forward rail riding surfaces.

The lower roller assembly includes self-aligning means consisting essentially of a shaft concentrically journaled between opposed. lower hoist brackets, the shaft including a pair of intermediate hubs each providing an axis offset from the journal axis and from the other hub.

The offset hubs are preferably disposed at to each other, and each offset hub provides a journal mounting for a rolling bearing carrying a rail-engaging roller element.

BRIEF DESCRIPTION OF THE DRAWING:

FIG. 1 is an elevational view of the hoist assembly;

FIG. 2 is a plan view taken on line 22 of FIG. 1;

FIG. 3 is a fragmentary plan view taken on line 33 of FIG. 1;

FIG. 4 is an enlarged fragmentary view of the self aligning roller assembly;

FIG. 5 is a diagramatic representation of the location of the rollers when the rails are aligned;

FIG. 6 is a diagramatic representation of the location of the rollers when the rails are misaligned an amount less than the combined eccentricity of the rollers; and

FIG. 7 is a diagramatic representation of the location of the rollers when the rails are misaligned an amount equal to the combined eccentricity of the rollers.

DESCRIPTION OF THE PREFERRED EMBODIMENT:

Referring now by characters of reference to the drawing and first to FIG. 1 it will be understood that the hoist and rail assembly includes a primary hoisting element 10. The self-aligning system can be applied to a conventional hoist loading platform or to a counterweight and the hoisting element 10 is representative of either one of these.

The hoisting element 10 is mounted to a pair of substantially upright rails 11 and 12, which are connected to a vertical wall 13 or similar support, by means of a plurality of rail brackets 14. The rail brackets 14 are connected to the rails at spaced intervals along their length.

A flexible cable 15 supports the hoisting element 10 in suspended, offset relation to the center of gravity G of said hoisting element by means of a pair of inclined upwardly projecting arms 16 and 17 connected by a cross member 18 having an apertured lug 20 disposed at the midpoint thereof.

The hoisting element 10 is movably mounted to the rails 11 and 12 by upper and lower roller assemblies 21 and 22. The upper roller assembly 21 is carried by a pair of outstanding brackets 23 and 24, which are attached as by welding to the arms 16 and 17, and the lower roller assembly 22 is carried by opposed brackets 24 and 25 respectively, which are bolted or otherwise attached to the lower end of the hoisting element 10.

Because of the rearward arrangement of the rail sup ports 14 it is desirable to provide the selflalignment feature on the roller assembly which engages the forward face of the rails 11. In the preferred embodiment therefore the self-aligning feature is built into the lower roller assembly 22 only.

The upper roller assembly 21 includes a pair of roller elements 29 which are carried by aligned stub shafts and which engage the rear faces 30 and 31 of the rails 11 and 12 respectively. The lower roller assembly 22 includes a pair of roller elements 27 and 28 which are carried by a common elongate shaft and which engage the forward faces 36 and 37 of said rails 11 and 12 respectively. The tendency of the hoisting element 10 to turn in a clockwise direction about its center of gravity G, because of the offset relationship of the point of suspension relative to said center of gravity, urges the upper and lower roller assemblies into engagement with their associated rail faces. The rails engaged by the vertically spaced roller elements resist the turning tendency and provide a couple resisting said turning moment. This arrangement insures that each roller is urged into engagement with its associated rail with a considerable force. For example, if the load supported by the cable 15 is 1,000 pounds and the perpendicular offset of the line of action of the force in the cable from the center of gravity G is 1 foot then the resulting turning moment will be 1,000 pounds feet. If the vertical spacing of the roller assemblies is set at feet, then, assuming that the rail faces are in alignment, each roller will be urged into engagement with its associated rail face with a force of 100 pounds. These forces can be utilized to actuate the self-aligning mechanism and urge the roller into equal bearing engagement with the rail faces when said faces are not in alignment as will be shown.

FIG. 4 illustrates the lower self-aligning roller assem bly 22 in some detail. The assembly includes an elongate shaft 36 comprising a tube 37 having an axis 38 and eccentric weldments 40 and 41 welded to each end of the tube 37. The weldments 40 and 41 are substantially identical but are fixedly attached to the tube 37 at an angular relation to each other of 180. Weldment 40 includes a journal end portion 42, rotatively mounted to the bracket 25 about a journal axis 43; an eccentric hub 44, having an axis 45 offset from the journal axis 43, and mounting the roller element 27; a retention flange 46, retaining the roller element 27; and an insert portion 47, having an axis 48 coaxial with the tube axis 38 and the journal axis 43. The roller element 27 includes a ball race 50 and a rail-engaging element 51. The eccentric Weldment 41 includes a journal end portion 52, rotatively mounted to the bracket 26 about an axis 53; an eccentric hub 54, having an axis 55 offset from the journal axis 53, and mounting the roller element 28; a retention flange 56 retaining the roller element 28; and an insert portion 57 having an axis 58 coaxial with the tube axis 38 and the journal axis 53. The roller element 28 includes a ball race 60 and a railengaging element 61.

It will be understood that, in effect, the shaft 36 includes oppositely cranked portions represented by axes 45 and 55, which are offset from the coaxial journal axes of rotation, axes 43 and 53.

As noted above, the offset suspension of the hoist results in a turning moment which is resisted by engagement between the spaced upper and lower roller assemblies 21 and 22 engaging associated rearward and forward rail surfaces respectively. If such associated rail surfaces, for example forward rail surfaces 32 and 33 in FIG. 4, are misaligned for a portion of their length, an amount L, the reaction force on the lower assembly 22 as a whole is momentarily unevenly applied to the roller elements. This out of balance force which could, in the example discussed above approach 200 pounds, is applied to the eccentrically related hubs to rotate the shaft assembly 36 about the common journal axes 43 and 53 until the forces are again balanced and the roller elements bear evenly on their associated rail surface with a force of 100 pounds. As the roller assembly 22 travels the rails the alignment differential between the rail surfaces is continuously compensated for by slight,

angular rotational movements of the journal end portions 42 and 52.

The combined offset between roller elements 27 and 28, as shown in FIGS. 5, 6, and 7, is indicated by E. The maximum misalignment L of rail surfaces 32 and 33, as shown in FIG. 4, which can be compensated for by the self-aligning system is thus equal to E and the relative disposition of the roller elements 27 and 28 in this condition is illustrated in FIG. 7. FIG. 5 illustrates the relative disposition of the roller elements 27 and 28 when the rail surfaces 32 and 33 are aligned and FIG. 6 illustrates the relative disposition of said rail elements when the rail surfaces are misaligned an intermediate amount. The provision of rolling bearings 50 and 60 permits relative rotation of the roller the roller elements 27 and 28 with respect to the shaft 36 and with respect to each other. The shaft 36 rotates only as necessary to permit equalizing rotation of the eccentric hubs 44 and 54.

As shown in FIG. 4 brackets 25 and 26 include cam follower assemblies 62 and 63 to preclude roller elements 27 and 28 from leaving the rails when the hoisting element 10 is subjected to side sway. Assembly 62 includes a projecting plate 64 apertured to receive a bolt 65 carrying a railengaging cam element 66. Assembly 63 similarly includes a projecting plate 67 apertured to receive a bolt 68 carrying a rail-engageable cam element 69. The upper brackets 23 and 24 include similar cam follower assemblies, generally indicated by numeral 72 in FIG. 1.

In order to preclude inadvertent forward movement of the hoisting element 10 under load relaxation conditions lower brackets 25 and 26 include back-up plates 74 and 75. Upper brackets 23 and 24 include similar back up plates indicated by numeral 76 in FIG. 1.

It is thought that the structural features and functional advantages of this hoist and rail assembly have become fully apparent from the foregoing description of parts but for completeness of disclosure the operation of the assembly will be briefly summarized.

The suspension of the hoisting element 10 in offset relation to its center of gravity G, provides a means of urging the upper and lower self-aligning roller assemblies 21 and 22 riding the rearward and forward rail surfaces into engagement with said surfaces. The hoisting element 10 thereby moves up and down the rail system with the roller elements under pressure. Cam follower assemblies, such as those indicated by numerals 62 and 63 in FIG. 2 adjacent lower brackets 25 and 26, preclude side sway of the traveling hoisting element 10. If rail misalignment exists at the lower end of the hoist 10, the lower roller elements 27 and 28 are maintained in engagement with their associated rails by means of the selfaligning mechanism. If rail misalignment exists at the upper end of the hoist 10 the upper roller elements 29 maintain engagement with their associated rails and the hoist is tilted slightly. The tilting is reflected at the lower end and is likewise taken up by the self-aligning mechanism. The system adequately compensates for differential rail misalignment thereby precluding excessive wear and racking of the hoisting element 10.

The preferred self-aligning assembly is shown in FIG. 4 to consist of eccentric hubs 44 and 54 which provide cranked axes 45 and 55 respectively offset l80 from each other, said axes providing the center of rotation about which roller elements 27 and 28 rotate. As

shown in FIG. 5, which illustrates the rails in alignment, the pressure roller forces resulting from the overturning moment on the hoist are spaced apart a distance equal to E, the combined eccentricity of the cranked axes 45 and 55. Any tendency for disengagement of a roller due to rail misalignment or slight tilting of the hoist results in compensatory rotation of the shaft 36 under the action of a righting couple provided by these roller forces and their reactions. The upward and downward passage of the hoist is therefore smooth and proceeds without any binding or racking. Moreover, because of the nature of the self-aligning mechanism, the provision of only one self-aligning roller assembly, for example at the lower end of the hoisting element 10, will ensure smooth travel of the hoisting element 10, even though a different degree of misalignment exists at the upper and lower locations.

I claim as my invention:

1. In a hoist and rail assembly:

a. a pair of substantially upright rails each including a forward face and a rearward face,

b. a hoisting element including a center of gravity and upper and lower bracket means disposed in spaced vertical relation to each other,

c. a lower self-aligning, rail-riding means including:

1. a shaft mounted in journal relation to the lower bracket means,

2. a pair of spaced eccentric hubs fixed to the shaft and disposed in offset relation from the shaft and angular relation to each other, and

3. a pair of spaced roller elements each being rotatively mounted to an associated hub for bearing engagement with one of an associated pair of rail surfaces,

d. an upper rail-riding means including:

1. a pair of aligned shafts mounted in journal relation to the upper bracket means, and

2. a pair of spaced roller elements each being rotatively mounted to an associated shaft for engagement with one of the other pair of associated rail surfaces, and

e. means urging the roller elements into engagement with the rail surfaces, including support means attached to the hoisting element in offset relation to the center of gravity.

2. In a hoist and rail assembly:

a. a hoisting element including bracket means,

b. self-aligning, rail-riding means including:

1. shaft means including an elongate shaft rotatively mounted in journal relation to the bracket means and having a pair of shaft portions with axes offset from the journal axis and disposed at substantially angular relation to each other,

2. a pair of spaced, rail-engaging elements each mounted to one of the shaft offset portions in rotative relation, and

c. means urging the rail-engaging elements into engagement with the rail surfaces. 

1. In a hoist and rail assembly: a. a pair of substantially upright rails each including a forward face and a rearward face, b. a hoisting element including a center of gravity and upper and lower bracket means disposed in spaced vertical relation to each other, c. a lower self-aligning, rail-riding means including:
 1. a shaft mounted in journal relation to the lower bracket means,
 2. a pair of spaced eccentric hubs fixed to the shaft and disposed in offset relation from the shaft and angular relation to each other, and
 3. a pair of spaced roller elements each being rotatively mounted to an associated hub for bearing engagement with one of an associated pair of rail surfaces, d. an upper rail-riding means including:
 1. a pair of aligned shafts mounted in journal relation to the upper bracket means, and
 2. a pair of spaced roller elements each being rotatively mounted to an associated shaft for engagement with one of the other pair of associated rail surfaces, and e. means urging the roller elements into engagement with the rail surfaces, including support means attached to the hoisting element in offset relation to the center of gravity.
 2. a pair of spaced eccentric hubs fixed to the shaft and disposed in offset relation from the shaft and angular relation to each other, and
 2. a pair of spaced, rail-engaging elements each mounted to one of the shaft offset portions in rotative relation, and c. means urging the rail-engaging elements into engagement with the rail surfaces.
 2. In a hoist and rail assembly: a. a hoisting element including bracket means, b. self-aligning, rail-riding means including:
 2. a pair of spaced roller elements each being rotatively mounted to an associated shaft for engagement with one of the other pair of associated rail surfaces, and e. means urging the roller elements into engagement with the rail surfaces, including support means attached to the hoisting element in offset relation to the center of gravity.
 3. a pair of spaced roller elements each being rotatively mounted to an associated hub for bearing engagement with one of an associated pair of rail surfaces, d. an upper rail-riding means including: 